1. Field of the Invention
The invention relates to socket wrench tools, and more specifically to wrench tools configured to prevent cross threading between nuts and studs.
2. Description of Related Art
It is known that many manufacturing processes call for the installation of threaded nuts onto threaded studs. Studs are fixed bolts projecting from a work piece for the purpose of fastening or location. Studs used in automated processes generally have starter points or "dog points" on their free end to aid location of the stud with the opening in the nut. Typically, a work piece containing a threaded stud is moved into a position where the stud is presented to receive a threaded nut. The work piece is held in place and a wrench tool containing a nut is advanced to the stud where the nut engages the dog point. Rotatably turning the nut with the wrench causes the nut to be run down the length of the stud thereby imparting clamp loads as is typical of threaded fasteners. The ideal wrenching process has the longitudinal axis of the stud in line with the rotation axis of the nut, thereby making it easier to locate the dog point and match the treads.
For a variety of reasons, misalignments often occur between the nut and the stud. A situation of particular concern has the nut face tilted away from perpendicularity with the axis of the stud. The rotation axis of the nut does not line up with the longitudinal axis of the stud leading to a mismatching between the nut threads and the stud threads. Some tilting of the nut relative to the stud can be tolerated without adverse consequences, but uncontrolled misalignments usually result in cross threading. The threads of the nut permanently damage the threads of the stud, or vice versa, by cutting across them rendering the fastener system ineffective or unusable.
No devices are known which have been developed specifically to prevent cross threading by automatically limiting misalignment between a nut and a stud. Many other devices are known however, that permit one handed wrenching of nuts and bolts. U.S. Pat. No. 1,097,288 to Bidinger discloses a ratchet wrench adapted with a notched portion which holds the head of a bolt thereby preventing rotation of the bolt when the nut is run down. This device, like others, requires that the nut be applied by hand before the tool can be used.
U.S. Pat. No. 1,282,523 to Bauer discloses a wrench for applying and removing nuts to bolts in inconveniently placed locations. The device has a first socket adapted to hold and rotatably turn a nut, and a fixed member with a second socket portion which opposes the nut for fixedly holding a bolt. The device is not well suited for automatically starting, and running down, a nut on a stud. The fixed member would physically interfere with the nut as the nut was run down. A clamp load would be applied to the second socket portion, and the tool would be fastened to the work piece.
It is desirable to construct a device which limits misalignment between a nut and a stud, the principle object of which being the prevention of cross threading therebetween. The value of such a device would be further enhanced if the device did not interfere with the run down of the nut on the stud.